This invention relates to the sampling, drainage or infusion of liquids from or to the human or animal body and in particular but not exclusively to a device for use in intravenous sampling or infusion via a cannula and to an adapter for use in connecting the device to a catheter.
It is known for a cannula to be used in sampling or infusion of liquids in a device in which the cannula communicates with a chamber having one or more ports through which a needle or catheter may pass into the cannula. In such devices liquid may be sampled or infused by connection to a drain or a source of liquid, respectively by means of a catheter. It has hitherto been a problem with such devices that an airlock may develop in the chamber or in the catheter. A further problem is that liquid may be lost during coupling of the device to catheters and the like and that under certain circumstances the loss of liquid may be hazardous, for example, when sampling blood from the body of an infective patient or when supplying potentially irritant medication with associated hazards to the patient and operator.